Diane Abbott was heckled by police officers today after wrongly claiming that the Met is the first force to allow spit hoods.

Speaking at the Police Federation annual conference in Birmingham, the Shadow Home Secretary was subjected to angry questions over her previous claims there was no evidence the mesh guards were "necessary or useful.”

Human rights campaigners have slammed the hoods, which cover a suspect’s head and prevent violent offenders from spitting and biting, as “distressing” and “degrading”.

Ms Abbott said she was "aware that spit hoods are a complex subject" and added that the Met is the first major force to bring them in.

Thames Valley Police and Hampshire Constabulary announced they were handing-out the mesh masks to their frontline staff, after 432 reports of their officers being spat at were recorded since April last year.

Me Abbott added: "I have never said I’m against them in principle, but like any fresh equipment and power I would want to see the evidence as to what they would do."

Broadcaster Ian Collins, who moderated the debate, told her "Can I just help you out? I’m not an expert on this but I think the theory is if someone spits in your face you use the spit guard to try to stop them doing it."

Groups, such as Liberty and Inquest, have argued that, in the past, hoods were often used unnecessarily and were used on disabled people and children.

But officers told Ms Abbott they were needed to protect from them contracting diseases and simply being spat at by violent offender.

Officers clashed with the Shadow Home Secretary over the use of spit hoods, pictured (Image: Herts Police)

One said: "It's about being spat upon. If you could bear that in mind I would appreciate it."

Ms Abbott stressed she had made no decision on the hoods and continues to examine the evidence.

But she got laughs from the delegates by making light of her claims in an LBC interview that Labour's pledge to employ 10,000 more officers would cost £300,000 over four years before correcting herself to "about £80m".